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Equalizers are very important and play a significant role in the electrical systems.

My coach is set up as a 24 volt house and chassis. Yet both have 12 volt current requirements. The Vanners allow 24 volt charging while maintaining the balance of voltage between all batteries. For example, both the chassis and house have sets of batteries wired in parallel and series so I have 12 and 24 volts available. Simply charging with a 24 volt alternator or charger will not assure all batteries will be maintained at the same voltage, so the Vanners are maintaining a very tight relationship between the 24 volt side of the battery bank and the 12 volt side. The Vanner maintains that relationship within 1/2 volt. If the 24 volt reading is 27 volts for example, the 12 volt reading is going to be 13.5 volts, plus or minus 1/2 volt.

Because of that Vanner equalizer, if you were to separate all of the batteries and take their individual readings, regardless of their state of charge (assuming they are all the same age and condition) all of their voltages would read the same.

If you have batteries in parallel such as four house batteries all supplying only 12 volts to the house there is no need for an equalizer.

Since my chassis has four batteries tasked with supplying 24 volts for things like starting the coach or powering the AC system, but also supplying 12 volts for things like the lights and DDEC the coach comes with one 100 amp equalizer, or on older vintage coaches it had 2 50 amp equalizers.

Prevosman, why a Vanner for a DDEC supply they don't care if they are 12V or 24V never saw a DDEC ran from a Vanner before ? good luck

Clifford I have to ask are you sure?

I'm not challenging your vast knowledge. Just that I've been told the exact opposite.I was told on our older DDEC's (8V92's an early 60 Series) that they are very picky about 12 V not getting below 12.1.

Now our newer buses have 24V DDEC units (or so I am told) and one of them is very finicky and if it ain't seeing 25+ volts it will crank all day and not start until I charge the batteries or put a booster box on it. Now the other will fire even if it gets down to 22 V so go figure.

Also not long ago we were experiencing HARD down shifts. (like throw ya outta the seat hard) And after the Allison dealer had it nearly 2 weeks and never found anything except low voltage codes. Then about the same time we discovered one of the alternators was going/gone bad.So I changed the alternator and it started shifting correctly again.About a week later the other alternator went out. (yeah I know shoulda changed them both at the same time.)

SO when I mentioned the alternators going out to Allison they immediately said "uh huh that's exactly why you were experiencing those hard shifts!" They also told me that the ATEC'c were very very sensitive to correct voltage an if they didn't have 12.5 or 25 V for which ever unit you had they would act up. BK

That is true about the older DDEC but they don't care where they get 12.1 volts can be from a 12 volt battery bank or a 24 volt bank all they do is stumble a little on start up with low voltage the ones I been around, my point was why a Vanner I never saw one tied to a Vanner always the batteries

Equalizers are very important and play a significant role in the electrical systems.

My coach is set up as a 24 volt house and chassis. Yet both have 12 volt current requirements. The Vanners allow 24 volt charging while maintaining the balance of voltage between all batteries. For example, both the chassis and house have sets of batteries wired in parallel and series so I have 12 and 24 volts available. Simply charging with a 24 volt alternator or charger will not assure all batteries will be maintained at the same voltage, so the Vanners are maintaining a very tight relationship between the 24 volt side of the battery bank and the 12 volt side. The Vanner maintains that relationship within 1/2 volt. If the 24 volt reading is 27 volts for example, the 12 volt reading is going to be 13.5 volts, plus or minus 1/2 volt.

Because of that Vanner equalizer, if you were to separate all of the batteries and take their individual readings, regardless of their state of charge (assuming they are all the same age and condition) all of their voltages would read the same.

If you have batteries in parallel such as four house batteries all supplying only 12 volts to the house there is no need for an equalizer.

Since my chassis has four batteries tasked with supplying 24 volts for things like starting the coach or powering the AC system, but also supplying 12 volts for things like the lights and DDEC the coach comes with one 100 amp equalizer, or on older vintage coaches it had 2 50 amp equalizers.

I'm not sure what the power rating is on this Vanner.. I haven't pulled it from my RTS yet and it has a cover over it so I can't see the numbers until I pull it out. Also, I am mainly just concerned about being able to run a couple 12V interior lights, cell phone, GPS, and am/fm stereo while puttering down the highway. There will be no house batteries..just the (2) 8D start batteries.

As to the question regarding 12 volts for DDEC. I do not know why on Prevost coaches, at least from the introduction of DDECI, up through my vintage DDECIII they use 12 volts. That's a nominal figure and the DDEC can still function with less than 12 volts, but I do not know at what specific voltage the cutout is.

I sense from some comments that the Vanner's function is misunderstood. The Vanner serves to maintain the voltage in the batteries in the entire battery bank at the same level regardless of whether the batteries are being charged, or if they have no input, but are merely being drawn down. Specifically, let's stick with DDEC. but this could apply to the use of lights or any current draw. The way the batteries are wired in parallel and in series it is possible to have a 12 volt load that is depleting the 12 volt circuit within the battery group. When that happens those batteries that are part of the 24 volt circuit will not be drawn down. So the Vanner in essence draws power from those batteries that are not necessarily loaded and "gives" it to the ones with the 12 volt loads so the voltage in every battery in the entire set is equal. Without the Vanner on a 12/24 volt battery set up the 12 volt batteries would be drawn down while the other batteries without a load would still have a charge. The Vanner equalizes the batteries when charging also whether the charge is from the engine alternator, a charger, or inverter/charger.

On my DDEC III coach my DDEC has power all the time, even when the master battery switch is turned off. This preserves certain data in DDEC. There are three circuits (notably CB 19, 20, 21) that remain hot. In fact when folks have a Prevost that decides to stop running the first thing I ask them to check are those three breakers because if any one trips the bus will not start or keep running if started. Those three are all 12 volt.

I am not saying this as an electrical engineer but as a layman that understands how equalizers contribute to the coach.

Depends on the unit some will cut out at 10 volts and some 9.5 when they start to stumble it is close to shutdown and if your clock battery is good they won't lose any data without power.The DDEC 1 is a different animal from the 11 or 111 but none care if it is 24 volt or 12 volt